PROBLEM - nvalid database connection group

Hi,

First of all, sorry for my poor english, ill try to do my best to explain my problems with ci 3.0.6.

I have done a fresh install on debian and im trying to use mysqli driver to do my db connections.

In config/database i have this parameters.

PHP Code:

$active_group = 'default';
$query_builder = TRUE;

$db['default'] = array(
    'dsn'    => '',
    'hostname' => '10.229.0.112',
    'username' => 'XXXX',
    'password' => 'XXXX',
    'database' => 'Informes',
    'dbdriver' => 'mysqli',
    'dbprefix' => '',
    'pconnect' => FALSE,
    'db_debug' => (ENVIRONMENT !== 'production'),
    'cache_on' => FALSE,
    'cachedir' => '',
    'char_set' => 'utf8',
    'dbcollat' => 'utf8_general_ci',
    'swap_pre' => '',
    'encrypt' => FALSE,
    'compress' => FALSE,
    'stricton' => FALSE,
    'failover' => array(),
    'save_queries' => TRUE
); 


In the model.

PHP Code:

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');


class Question_model extends CI_Model
{
    public function __construct()
    {
        parent::__construct();
        $this->load->database('default');
    }

    // Metodo que devuelve todas las filas de la tabla Pregunta en questionWeb
   public function setResponse($pregunta,$usuario,$respuesta)
   {
      
      
      if ($respuesta=="zero")
      {
        $respuesta="0";
      }
      $consulta=$this->db->query("INSERT INTO RespuestasFIN values(".$pregunta.",'".$respuesta."','".$usuario."')");

      if ($this->db->affected_rows() == 1)
        {
          return true;
        }
   }

}

?>

And when i try to execute my controller, it shows me this error:

You have specified an invalid database connection group (questionWeb) in your config/database.php file.

I dont understand why it talks about "questionWeb" when my group connection is "default" :S.

Can anyone help me?

Sorry for my english!